Neandertalized ‘Mini Brains’ Yield Clues to Modern Human Uniqueness

Experiments on clusters of cultured cells hint that a gene variant found only in 

Homo sapiens profoundly changed brain development in our species, compared with our extinct relatives

Cortical organoids carrying archaic NOVA1 (left) and modern NOVA1 (right) differ in shape and in neuron development. Credit: U.C. San Diego Health Sciences

We take it for granted that Homo sapiens is the only human species in existence, but it didn’t use to be this way. From the origin of our species a few hundred thousand years ago until a few tens of thousands of years ago, multiple human species shared the planet with our own. What distinguished H. sapiens from other members of the human family, and why did our lineage alone survive to the present day? Scientists have long sought answers to these questions in the fossil and archaeological records. More recently they have started mining the genomes of living and extinct humans—including the Neandertals—for clues.

The Neandertals and the lesser-known Denisovans are our closest evolutionary relatives, so we share a lot of DNA in common with them. But we also have alleles, or genetic variants, that are unique to H. sapiens. Research published online today in Science has identified these sapiens-specific variants and homed in on one in particular that may have brought about a pivotal change in the way our brain develops.